SANTA MONICA, Calif., May 7, 2000 -- A last link to Hollywood's old-school glamour years is gone. Douglas Fairbanks Jr., spawn of "The Black Pirate," stepson of America's Sweetheart, onetime husband of "Mommie Dearest" and a film star in his own right, died today in New York. He was 90. Fairbanks appeared in more than 80 films and TV movies, including the 1939 adventure classic "Gunga Din." He was perhaps best known, though, for being dapper and for doing the dapper thing in the company of gian